1,720,962 research outputs found
Study of magnetic anisotropy and magnetism of Fe in Ni/Fe/Ni(111) trilayers by Mössbauer spectroscopy
No full textThe hyperfine field and the magnetic anisotropy of a Fe layer as a function of thickness have been investigated in several Ni/57Fex/Ni(1 1 1) trilayers with relatively thick Ni layers by Mössbauer spectroscopy. For Fe layers with thickness below 16 Å, the Mössbauer spectra show always the presence of two ferromagnetic phases with high-spin state. In the range between 6 and 8 Å, also a ferromagnetic phase with low-spin state and a paramagnetic phase have been found. The evolution of the mean hyperfine field of the 57Fe nuclei is used to study the Fe growth. A structural FCCBCC phase transition is found to begin with an iron thickness of 8 Å. The easy direction of the magnetization is found out-of-plane for Fe interlayer with FCC structure, and perfectly in plane for Fe interlayer with BCC structure. © 2002 Elsevier Science B.V. All rights reserved
Oxidation-State and Short-Range Order at the Surfaces of Amorphous Fe40Ni40P14B6 Ribbons
No full textConversion electron Mossbauer spectroscopy (CEMS) was used to study the oxidation state at the surfaces of amorphous Fe40Ni40P14B6 ribbons obtained by melt-spinning in air and vacuum heated at 583 K. Different concentrations of ferric and ferrous ions depend on the different behaviour of phosphorous diffusion towards the two surfaces during low annealing temperature
Short-Range Order at the Surfaces of Annealed Amorphous Fe40Ni40P14B6 Ribbons
No full textConversion electron Mossbauer spectroscopy (CEMS) and gamma transmission Mossbauer spectroscopy were used to measure the effects of annealing at 583 K in vacuum into about 200 nm thick layer below the two surfaces and on the bulk of the Fe40Ni40P14B6 amorphous ribbons prepared by means of melt-spinning technique. The results show a large distribution of hyperfine magnetic fields on the bulk and in the surfaces of the samples. By means of selective analysis of hyperfine magnetic field distribution, we have evalueded the correlation between the different degree of short range orders at the surfaces and in the bulk of the samples, and the phosphorus segregation associated with mechanical enbrittlement induced at low annealing temperature
Static magnetization direction in fcc (111) Fe/Ni multilayers
No full textThe rotation of the static magnetization was measured by Mossbauer spectroscopy as 2.5 monolayers of resonating Fe-57 were moved from inside the Fe films to the Fe/Ni interfaces in Fe/Ni (17/200 angstrom) multilayers produced by thermal evaporation. The results indicate a remarkable dependence of the tilt angle as a function of distance from the surface
Development of interface-induced out-of-plane magnetic anisotropy in Ni/Fe/Ni trilayers
No full textThe magnetic properties of trilayers Ni(1000 Å)/57Fe(x Å)/Ni(200 Å) grown by evaporation in ultra-high vacuum, have been investigated using Mössbauer spectroscopy, magneto-optic Kerr vector-magnetometry, and magnetic force microscopy (MFM). The data measured from a sample with Fe thickness x = 6 Å show the development of an out-of-plane anisotropy that tends to align the magnetization of the 57Fe at about 40° respect to the normal to the layer plane. For higher 57Fe layer thickness the data indicate that the magnetization lies in the film plane. The magneto-optic measurements and the MFM images demonstrate also that when x = 6 Å the 57Fe layer induces a reorientation of the magnetization of the Ni outermost layer from in-plane to out-of-plane. The results are interpreted as due to anisotropy effects induced at the interface Fe/Ni and to the γ → α transition that takes place between 6 and 16 Å. © 2001 Elsevier Science B.V. All rights reserved
The Ni-Gamma-Fe Interface - Hyperfine Magnetic-Field And Magnetic-Anisotropy
No full textConversion Electrons Mossbauer Spectroscopy (CEMS) is used to study the magnetic polarization state and the magnetic anisotropy of ultrathin Fe/Ni films in multilayer samples with two, one and any Fe/Ni interface. The analysis of the distribution function of the hyperfine fields indicates a magnitude of 34 T for the Fe/Ni interface field and gives evidence of the existence of a pure, highly susceptible gamma-Fe phase. Results corresponding to intermixed regions suggest enhanced hyperfine fields and magnetic moments in local environments with more than 6 and up to 9 nearest Fe neighbor atoms, and low fields in Fe sites with 10-11 Fe neighbors. Out-of-plane perpendicular anisotropy is found only in samples having an Fe/Ni interface
Structural relaxation effects on the hyperfine parameters in Fe80B20 amorphous alloys
No full textWe have studied the influence of the relaxation effects on the different kinds of short range order structures which can be distinguished inFe 80 B 20 amorphous alloys by Mössbauer spectroscopy. The analysis of the distribution function of the hyperfine fields gives results on the variations of the chemical and topological short-range orders in good agreement with those known in literature. Attempt to give quantitative results is made
Magnetic properties of Fe/Ni multilayers grown on mylar
No full textNi200/Fe16 (angstrom) multilayers were prepared by thermal evaporation in high vacuum onto mylar substrates at room temperature (RT). CEMS spectra at RT show the coexistence of several magnetic phases and out-of-plane magnetic anisotropy of the iron layers. SQUID measurements in the 4.2-350 K temperature range show in-plane magnetization of the Ni layers and a magnetic phase transition near 300 K
Magnetic-Behavior of Iron-Nickel Multilayers
No full textWe have studied the magnetic behaviour of Ni/Fe multilayers in both high and low magnetic fields. The results obtained in high magnetic fields suggest in plane anisotropy typical of homogeneous magnetic thin films, those ones obtained in low fields give evidence for an antiferromagnetic coupling among the Ni layers near to the room temperature
Magnetic-Properties of (111)Cu/Fe Multilayers
No full textThe magnetic properties of (111)Cu/Fe multilayers grown on Cu underlayers of several thickness (2000-500-50 angstrom) on cleaved mica have been investigated by Mossbauer spectroscopy and SQUID magnetometry. The analysis of experimental results suggests that 2.5 monolayers of gamma-Fe interfaced with Cu evolves partially from paramagnetic to ferromagnetic states as the Cu underlayer thickness is reduced to 50 angstrom and partially from weak to strong antiferromagnetism
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